Compressor unloader



Patented Jain.l ll, 1927.

UITED STATES PATENT OFFICE..

CHESTER W. METZGAR, OF EASTON, PENNSYLVANIA, ASSIGNOR TO INGERSOLL-RAND COMPANY, OF JERSEY CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY.

COMPRESSOR UNLOADER.

Application led` November 3, 1925.

This invention relates to compressors, but more particularly to an unloader for compound compressors capable of also acting as.

passages of the cylinders so vthat both cyl-4 inders discharge into the intake passage of the low pressure cylinderv for unloading purposes. The advantage of unloading into the intake passage of the low pressure cylinder resides in the fact that the noise is greatly reduced and the unloading is made almost A silent.

The construction andarrangement of the by-pass unloading connections aifords a ready and convenient means for locating the unloading valves in saidconnections in such manner that small space is taken up on the compressor cylinders in case said valves are mounted on the cylinders which is the pret'- '25 `erable construction. For starting purposes, in casevthere is no pressure in the receiver,

the unloading valves may be maintainedv closed either by hand oper-ated devices'or by a valve controlling the automatic con- -nections from the receiver to an auxiliary valve, which is normally responsive to receiver pressure for maintaining the unloader valves closed.

The invention is shown in one of its preferred forms in the accompanying drawing which' is a diagrammatic representation partly in longitudinal sectional elevation and partly -broken away of the unloader.

Referring to the drawing, the' low pres- 40 sure cylinder A and the high pressurecylinder B are in this instance provided with a trunk piston C having the connecting rod D and adapted to be driven in any suitable manner, as-for instance by means of an oil engine. The drawing is intended to indicate an oil engine driven compressori The low pressure cylinder A isprovided with tlie inlet valve or valves E and the discharge valve or valves F of which there may 4 sired.

Serial No. 66,496.

be any desired number of any suitable type, as for instance, plate valves. The intake Gr of the low pressure cylinder communicates with the intake passage H and the discharge passage J for said cylinder communicates with the passage K leading to the intercooler L. The passage O from the intercooler communica-tes through the intake passage P of the high pressure cylinder with the high pressure intake valve or valves Q. The discharge passage R of the high pressure cylinder is provided with the discharge valve or valves S and is connected to the receiver T by the usual pipe U.

A by-pass connection V'is formed in the head of -the low pressure cylinder A connecting the discharge passage J with the inlet passage H and in this by-pass connection is located an unloading valve W of any suitable orm which may be both manually and automatically controlled. A'by-pass connection X is also provided in the cylinder walls from the high pressure cylinder B to the discharge passages J and K and a similar unloading valve Y both manually and automatically controlled is provided at this point .so that when both unloading valves lVV and Y are open both high and low pressure cylinders are unloaded and discharge through said by-pass connections and unloader discharge passages to the intake G of the compressor.

' The unloading valves W and vY comprise the valve seats a having the guides b between which and the valves are located the compression s rings cr The valve casings Z opntain lthe p ungers e having the stems f bearing on the valves andV hand wheels g form manual means for closing the unloading valves and maintain them closed when de- An auxiliary valve Z responsive to recciverpressure from the ipe It and connected by the pipes j an to the valve casings d at the points o and p respectively, moves the plungers e inwardly `due to r'eceiver pressure and maintains the unloading valves4 closed under normal conditions. Re-

lease of pressure from the plungers e of the' space a: is always subject to receiver pressure and a compression spring y tends to move the valve member 7' to a position to open the space a: to the port v and admit receiver ressure through the pipes and c for closmg the unloader'valves. A pressure uid connection e frein the pipe z, to the chamber 3 in the auxiliary valve casing supplies pressure through the small port 4 against an 'opposite head t of the valve member r to force the valve member in the opposite direction to the position indicated in the drawing, in which the shoe u connects the ports 'o and w so that pressure is released from the plungers e through the atmospheric port w and the unloader'valves are permitted to `open under the influence of the valve springs c as indicated in the drawing.. A

leak port 5 is in the casing g and a dia.Y

phragm carrying a needle valve 7 is located in the chamber 3. A spring 8 above the diaphragm 6 is regulated by the set screw 9 so that the needle valve 7 normally closes the small port 4 and upon an increase of pressure in the receiver beyond a prede-- termined point, the diaphragm 6 retracts the needle valve 7 and opens the small port 4 admitting receiver pressure against the valve head t to Vtorce the valve to the position indicated in the drawing connecting the ports vaud lw. Upon reduction of receiver pressure to a predetermined point the diaphragm 6 closes the port 4 by means ot the needle valve 7 and due to the leak port 5 the spring y actuates the valve member r.

A.v three-way cock 10'01- other suitable device is rovided in the receiver pressure line 'rfor starting purposes, when starting the compressor under discharge line pressure. If there is no pressure in the discharge line,

the unloadingvalves W and Y will be open.

when starting, but for starting under d ischarge line pressure the three-way cock 10 is turned to release the pressure against the unloader .Valve plungers c andpermit the unloading valves to open and remain open until the engine comes up to speed, at which time the unloading valves YV and Y are closed by the hand wheels f/ until pressure is built up in the receiver. 'I he hand wheels are then backed oil' so that the unloading valves will operate automatically from the auxiliary valve Z.

In the operation ol' the device, let it be assumed that there is pressure' in-the receiver T and the compressor is running normally. An increase of pressure in the receiver T bevond the predetermined point will cause the needle valve 7 of the auxiliary valve Z to open the port 4 and cause the valve member. r to assume the position shown in the drawing so that pressure is relieved from the unloading valve plungers e and the unloading valves W and Y automatically open for unloading the cylinders, through the by-pass connections described and upon a reduction of pressure in the rcceiver to a predetermined point the unloading valves will automatically close.

I claim: v

l. In al compound compressor, the combination of high and low pressure cylinders, inlet and discharge valves therefor, an intercoo1era by-pass connection in the wall of the low preSS'ure'cyHnder connecting the inlet and discharge passages of said cylinder,-

an unloading valve located in and control-l ling said by-pass connection, whereby the low pressure cylinder dischar es through the discharge 4valves and said y-pass connections into the intake passage for unloading when the unloading valve is open, a second ily-paas. connectionfin the wall of the high pressure4 cylinder leading from the high pressure cylinder to the discharge pascage of the low pressure cylinder, and an unloading valv'elocated in and controlling said second by-pass connection, whereby the high pressure cylinder also discharges into the intake passage of the low pressure cylin- `der for unloading when both. unloading Valves are open.

2; In a compound compressor, the combination ot high and low pressure cy1inders inlet and discharge valves therefor, an intercooler, a by-pass connection in the wall of. Y

the low pressure cylinder connecting the inlet and'discharge passages of said cylinder, an unloading valve located in and controlling said by-pass connection, whereby the low pressure cylinder discharges through the discharge valves and saidjlo -pass con nection into the intake passage 'or unloading when the unloading valve -is open, a second by-pass connection in the wall of the high pressure cylinder leading from the high pressure cylinder to the discharge passage of the low pressure cylinder, an unloading valve located in' and controlling said second by-pass connection, whereby the high pressure cylinder also discharges into the intake passage of the low pressure cylinder for unloading when both unloading valves are open, and automatic means responsive to receiver pressure for automatically controlling both ci' said unloading valves torboth cylinders.

3. ln a compound compressor, the combination of high and lowprcssure cylinders, inlet and discharge valves therefor. an interH cooler. a bypass connection vin the wall Ui* high pressure cylinder to the discharge pash sage of the low pressure cylinder, an unloading valve located in and controlling said second by-pass connection, whereby'the high pressure cylinder also discharges into the intake passage of the low pressure cylinder for unloading when both unloading valves are open, and combined manual and, pressure fluid automatically actuated mens for controlling said unloading valves for both cylinders.

In testimony whereof I have signed this specification.

CHESTER W. METZGAR. 

